Q. If a student is selected at random from a group of 15 students, where 9 are girls and 6 are boys, what is the probability that the selected student is a boy? (2021)
A.
1/3
B.
2/5
C.
1/2
D.
3/5
Solution
Probability of selecting a boy = Number of boys / Total students = 6/15 = 2/5.
Q. If a student is selected at random from a group of 15 students, where 9 are girls and 6 are boys, what is the probability that the student is a boy? (2023)
A.
2/5
B.
1/3
C.
1/2
D.
3/5
Solution
Probability of selecting a boy = Number of boys / Total students = 6/15 = 2/5.
Q. If a student is selected at random from a group of 40 students, where 25 are girls and 15 are boys, what is the probability that the selected student is a boy?
A.
3/8
B.
1/2
C.
3/5
D.
1/3
Solution
Probability of selecting a boy = Number of boys / Total students = 15/40 = 3/8.
Q. In a family with 3 children, what is the probability that at least one of them is a girl?
A.
1/8
B.
1/2
C.
7/8
D.
3/8
Solution
The only scenario where there are no girls is if all three children are boys, which has a probability of (1/2)^3 = 1/8. Therefore, the probability of having at least one girl is 1 - 1/8 = 7/8.
Q. In a group of 50 people, 30 like tea, 20 like coffee, and 10 like both. What is the probability that a person chosen at random likes either tea or coffee?
A.
1/2
B.
3/5
C.
4/5
D.
1/5
Solution
Using the principle of inclusion-exclusion, P(Tea or Coffee) = P(Tea) + P(Coffee) - P(Both) = (30/50) + (20/50) - (10/50) = 40/50 = 4/5.
Understanding Probability Rules is crucial for students preparing for school exams and competitive tests. Mastering this topic not only enhances your problem-solving skills but also boosts your confidence in tackling objective questions. Practicing MCQs related to Probability Rules helps you identify important questions and solidify your exam preparation.
What You Will Practise Here
Basic concepts of probability and its significance
Types of probability: theoretical, experimental, and subjective
Key formulas for calculating probabilities
Conditional probability and independence of events
Bayes' theorem and its applications
Common probability distributions: binomial and normal
Real-life applications of probability in decision making
Exam Relevance
Probability Rules are a significant part of the curriculum for CBSE, State Boards, NEET, and JEE. Questions often focus on calculating probabilities, applying formulas, and interpreting data. You can expect multiple-choice questions that test your understanding of concepts and your ability to solve problems efficiently. Familiarity with common question patterns will give you an edge in your exam preparation.
Common Mistakes Students Make
Confusing independent and dependent events
Misapplying the formulas for conditional probability
Overlooking the importance of sample space in calculations
Failing to distinguish between theoretical and experimental probability
FAQs
Question: What are the basic rules of probability? Answer: The basic rules include the addition rule, multiplication rule, and the concept of complementary events.
Question: How can I improve my skills in solving Probability Rules MCQs? Answer: Regular practice with objective questions and understanding the underlying concepts will significantly enhance your skills.
Start solving Probability Rules practice MCQs today to test your understanding and improve your exam readiness. Remember, consistent practice is the key to success!
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